Biomedical subjects

A Hammond

Publications and source records attributed to A Hammond.

14 recordsLinked to original sources

PubMed1992

The presence of uracil-DNA glycosylase in insects is dependent upon developmental complexity.

The metamorphosis of insects can, in a general way, be divided between those organisms that undergo pupation accompanied by cellular histolysis and those that gradually develop into adults without an intervening pupal stage of development. In the former case, the death of a cell population is an integral part of development that is tightly associated with massive DNA degradation during pupation. In that regard, it has been suggested that uracil-containing DNA acts as a target for the nucleolytic breakdown of DNA during histolysis in insects (Deutsch, W. A. (1987) Mutat. Res. 184, 209-215), thus placing into question how compatible the existence of uracil-DNA glycosylases would be for this form of developmental signal. As a result, we tested for the presence of a uracil-DNA glycosylase in insects representative of those having an intervening pupal stage of development and those that do not. We show here that a nonpupating insect contains a uracil-DNA glycosylase activity. Conversely, crude extracts of Drosophila melanogaster, as well as of three other insect populations that undergo pupation similar to that found in Drosophila, do not contain detectable levels of this DNA repair activity. Thus, there appears to be a consistent correlation between cellular destruction during development and the absence of a uracil-DNA glycosylase, which supports the possibility that uracil-containing DNA may play an important role in those cells targeted for death.

Animals↗

PubMed1992

Effects of C4 null alleles and homoduplications on quantitative expression of C4A and C4B.

The availability of MoAbs now allows the accurate quantification of the individual C4 isotypes, C4A and C4B. Using a sensitive two-site immunoradiometric technique to measure serum levels of C4A and C4B, we studied the relationship between genotype and phenotype and physiological factors affecting C4 expression in 129 fully genotyped healthy subjects. Our results confirm that there is extensive phenotypic overlap between genotypic groups and it was not possible to determine the presence of single null alleles from total serum C4. Of the factors which may influence C4 expression, we found that age contributes a very small influence but that gender has no effect and there was no evidence for the presence of feedback of null alleles on the expression of remaining genes. Potential problems in quantifying C4 arising from the complex relationship between isotypic identity and serotypic recognition were highlighted by the finding of reversed antigenic expression of a C4B*5 molecule which was recognized as C4A by the anti-Rg:1 monoclonal used in these studies. We also confirmed that the extended MHC haplotype associated with Felty's syndrome, HLA-B44, C4A*3, C4BQ*O, HLA-DR4, encodes an expressed, duplicated, C4A gene.

Adult↗

PubMed1992

Keratan sulphate in rheumatoid arthritis, osteoarthritis, and inflammatory diseases.

Serum concentrations of antigenic keratan sulphate determined by an enzyme linked immunosorbent assay (ELISA) with a monoclonal antibody were studied in patients with rheumatoid arthritis (RA), osteoarthritis, ankylosing spondylitis, other inflammatory diseases, and a large control group of women without arthritis. Mean keratan sulphate concentrations were low in 117 women with RA compared with 227 female control subjects matched for age drawn from a community survey. There were significant correlations between serum keratan sulphate concentrations in patients with RA and serum C reactive protein and the erythrocyte sedimentation rate. Serum keratan sulphate concentrations were also low in 29 men and women with ankylosing spondylitis and 29 patients with arthritis and high concentrations of C reactive protein. In 98 women undergoing an operation for benign breast disease there were decreases in serum keratan sulphate concentrations after the operation which correlated with doses in serum C reactive protein. No differences were found in keratan sulphate concentrations in 137 women with osteoarthritis compared with controls. Within the group with osteoarthritis there were no differences for the various joint groups and there was no obvious correlation with radiographic severity or progression. These findings suggest serum keratan sulphate is unlikely to be useful as a diagnostic marker in osteoarthritis or RA but indicate a role for inflammation in the regulation of cartilage loss.

Acute-Phase Reaction↗

PubMed1991

[Purulent parotitis in an infant].

A sibling was taken into hospital at the age of 3 weeks with an acute suppurative parotitis of the left parotid. Since birth, the child had suffered from recurrent infections. Her mother was known with recurrent furunculosis. Ultrasonography of the left parotid showed a diffuse enlarged parotid with multiple areas of necrosis. After a diagnostic puncture, a penicillin resistant Staphylococcus aureus was found. Therapy consisted of intravenous antibiotics.

Female↗

PubMed1990

Immunization against hepatitis B--what can we expect? Results of a survey of antibody response to immunization in persons 'at risk' of occupational exposure to hepatitis B.

One thousand three hundred and twenty adults at risk of occupational exposure to hepatitis B were immunized using genetically engineered surface antigen and their antibody response (anti-HBs IU/l) assessed. Sex was known for all subjects and age for 1120 (range from 17-71 years). Seven hundred and sixty-four subjects were immunized in the local Department of Occupational Health, the remainder mainly by general practitioners. Analysis of 'good responders' (anti-HBs greater than 100 IU/l) according to age and sex showed that increasing age and male sex had independent adverse effects on the likelihood of developing a satisfactory level of antibody to HBsAg. Furthermore even those most likely to respond well (young women), had a 1/5 to 1/6 failure rate to achieve greater than 100 IU/l anti-HBs. Of 63 persons who received a fourth dose of vaccine, 26 developed anti-HBs titres greater than 100 IU/l when tested after 6 months. Subjects who had a low level of anti-HBs following primary immunization were more likely to develop greater than 100 IU/l anti-HBs following a booster dose than were non-responders (less than 10 IU/l).

Adolescent↗

PubMed1989

Reduced numbers of complement receptor type 1 on erythrocytes are associated with increased levels of anticardiolipin antibodies. Findings in patients with systemic lupus erythematosus and the antiphospholipid syndrome.

In several diseases, including systemic lupus erythematosus (SLE) and autoimmune hemolytic anemias, the numbers of complement receptor type 1 (CR1) expressed on erythrocytes of patients are reduced. In patients with SLE, anticardiolipin antibodies (aCL) have been associated with positive results on direct antiglobulin tests. Because of these findings, we investigated whether the reduced expression of erythrocyte CR1 in 61 patients (53 with SLE and 8 with the antiphospholipid syndrome) might be associated with the presence of aCL. A negative correlation was observed between aCL levels and mean numbers of CR1 (rs = -0.43, P = 0.001), and a positive correlation was observed between aCL levels and the levels of erythrocyte C4d and C3d (rs = 0.33 and 0.41, P = 0.01 and 0.001, respectively), but no correlation of aCL levels with serum C4 levels was found. When the results were further analyzed according to the IgG or IgM class of aCL, levels of antibodies of both classes were negatively correlated with CR1 numbers, but only IgM aCL levels were correlated with erythrocyte C4d and C3d numbers. The levels of anti-double-stranded DNA antibodies showed no correlation with erythrocyte CR1, C4d, or C3d numbers but were negatively correlated with serum C4 levels (rs = -0.43, P = 0.002). These data suggest that aCL, or a closely related antibody specificity, may bind to erythrocytes and may be directly involved in the mechanism for reduction of erythrocyte CR1 expression in SLE patients.

Antibodies, Antinuclear↗

PubMed1989

Subarachnoid haemorrhage--can we do better?

Patients with subarachnoid haemorrhage often have warning symptoms which are unrecognized. Specific neurological signs such as cranial nerve palsies due to aneurysm expansion may occur. Sudden and severe 'out-of-the-blue' headache following minor haemorrhage may be misinterpreted as migraine. Focal neurological signs from secondary ischaemia may be misinterpreted as thromboembolic events. Computed tomography (CT) head scans can be misleading especially if performed too late.

Adult↗

PubMed1989

[Recurrent hepatitis A].

A 14 year old Turkish girl was diagnosed to have hepatitis A according to symptoms and positive serology. She had a clinical and biochemical relapse eight weeks after the first manifestation of the disease. Relapsing hepatitis A is very rare but it does not alter the usual favourable outcome.

Adolescent↗

PubMed1986

Palliative topical and systemic misonidazole with low-dose irradiation for recurrent carcinoma of the cervix uteri.

This report concerns a determinate series of 11 patients with progressive recurrent cancer of the cervix uteri, who were treated with misonidazole (1 g) applied locally for 24 hours and an oral dose of 2.9 g/m2 four hours before a single mid-plane dose of 5.00 Gy. Four of 11 (36%) remained free of disease at one year. It is suggested that this is largely a hypoxic cell cytotoxic effect and is a useful method of palliation.

Carcinoma, Squamous Cell↗

PubMed1986